1. Field of the Invention
An aspect of the invention is related to a data transfer apparatus, a data transfer method and a recording medium having a data transfer program recorded thereon, by which pieces of untransmitted data are extracted from a plurality of contents as transmission targets and transmitted to a plurality of mobile terminals through a transmission line, respectively.
2. Description of the Related Art
With advances such as smaller size and higher function of terminals such as portable phones, personal computers or PDAs in recent years, and the development of wireless network technology, various content which could be used heretofore only in a wired environment have been used easily also in a mobile environment such as the outdoors or travel destination. For example, digitization of paper manuals and storage of these digitized manuals into a server unit have been conducted in a maintenance service of a company. Thus, when a worker uses a mobile terminal to access the server unit to download contents from the server unit to the mobile terminal, the worker can acquire necessary contents easily from travel destination. As a result, it is not necessary for the worker to carry a large amount of paper manuals with him/her anymore.
On the other hand, as the size (data capacity) of contents to be downloaded increases, download time from the start of download to the end of download increases. That is, the worker cannot use the contents unless the download is completed. For example, in a maintenance service of a company, the worker needs to go to a customer's place and repair a product as soon as the worker accepts a customer's request to repair the product. If the worker cannot depart before completion of the download, however, this leads to lowering of quality of the maintenance service. In addition, even if the worker started the download after arrival at the customer's place, the download would take a long time. Consequently, the start of the work repairing the product would be late, causing a lowering of quality of the maintenance service.
Therefore, there has been known a technique in which a worker neither departs after completion of a download nor starts the download after arrival at a destination. The worker, rather, starts the download during the worker's travel, in order to complete the download before arriving at the destination. Specifically, the worker first registers travel schedule information about a departure place, a travel destination, a travel start time, a travel means, etc. into a distribution center in advance. The distribution center calculates an estimated time of arrival based on the registered travel schedule information. The distribution center calculates a distribution time based on the estimated time of arrival and distributes contents to a mobile terminal at the time point when the current time just coincides with the distribution time in accordance with a timer. Thus, the worker can use the contents as soon as the worker arrives at the destination.
Such a technique has been disclosed, for example, in JP-A-2001-298775, JP-A-2003-158777 and JP-A-2004-193995.
In the related-art method, however, only the timing for starting distribution of the contents is controlled. Accordingly, in the case where, for example, the moving velocity of the mobile terminal increased during download, there was a possibility that the download would not be completed when the user of the mobile terminal arrived at the destination. In addition, in the case where, for example, another mobile terminal started downloading during the download, there was a possibility that the download would not be completed when the user of the mobile terminal arrived at the destination, because part of a total bandwidth of a communication line had been already spent by the other mobile terminal's download.